Retorting oil shale including agglomerated fines

ABSTRACT

A SYSTEM IS DISCLOSED FOR RECOVERING OIL FROM OIL BEARING SHALE ROCK IN WHICH THE ROCK IS SCREENED TO SEPARATE FINES FROM LARGER PARTICLES HAVING A DIMENSION OF AT LEAST ABOUT 1/4 INCH. THE SYSTEM INCLUDES A RETORTING ZONE IN WHICH HEATED GASES, REDUCING OR NEUTRAL, ARE PASSED THROUGH THE LARGER PARTICLES AND AGGLOMERATES OF THE FINES TO HEAT THESE PARTICLES AND AGGLOMERATES TO OIL EDUCING TEMPERATURE AND AFTER WHICH THE GASES, THEN CONTAINING EDUCTED OIL, ARE PASSED THROUGH A ZONE IN WHICH PARTICLES AND AGGLOMERATES ARE PREHEATED AND THE GASES COOLED TO CONDENSE THE OIL TO SMALL DROPLETS AND VAPOR IN THE GASES THE OIL IS SEPARATED FROM THE GASES AND INTO VARIOUS FRACTIONS. THE HEAVIEST FRACTION OF THE OIL, REPRESENTING AN AMOUNT IN A RANGE OF FROM ABOUT 5% TO 50% OF THE TOTAL OIL EDUCTED, ARE RECIRCULATED THROUGH THE SYSTEM BY USING SUCH OIL AS BINDER TO AGGLOMERATE THE FINES INTO AGGLOMERATES AT LEAST 1/4 INCH. THESE AGGLOMERATES MAY DBE ADVANTAGEOUSLY UTILIZED BY CHARGING THEM TO A TRAVELING GRATE APPARATUS WITH THE LARGER PARTICLES TO FORM A BED, WITH THE AGGLOMERATES FORMING AN INTERMEDIATE LAYER BETWEEN UPPER AND LOWER LAYERS OF THE LARGER PARTICLES. THE LARGER PARTICLES WILL, IN A PREHEATING-CONDENSING ZONE, TRAP AND PREVNET ESCAPE FROM THE BED, DUST AND DROPS OF HEAVY BINDER OIL (WHICH MAY ESCAPE FROM AGGLOMATES). WITH EITHER AN UPFLOW OR DOWNFLOW OF GAS IN THIS PREHEATING-CONDENSING ZONE, HEAVY BINDER OIL ATTEMPTING TO ESCAPE THE BED WILL ADHERE TO AND COAT PARTICLES IN THE UPPER OR LOWER LAYERS AND DUST ATTEMPTING TO ESCAPE THE BED WILL ADHERE TO THE LARGER PARTICLES COATED BY THE HEAVY BINDER OIL. THUS, BOTH THE HEAVY BINDER OIL AND DUST ATTEMPTING TO ESCAPE IN THIS PREHEATING-CONDENSING ZONE WILL BE TRAPPED IN THE BED. IN THE RETORTING ZONE SUCH HEAVY FRACTION BINDER OIL RETAINED IN THE BED WILL PYROLYZE TO PRODUCE FURTHER USEFUL LIGHTER OIL WHICH WILL LEAVE THE BED AS VAPOR, AND RESIDUAL COKE WHICH WILL REMAIN IN THE BED.

RETORTING OIL SHALE INCLUDING AGGLOMERATED FINES Filed June s. 196e Feb.2,1971 C, A, ROWLAND ETAL 2 sheets-sheet 1 RETORTING OIL SHALE INCLUDINGAGGLOMERATED FINES Filed June 5. 1968 C. A. ROWLAND ETAI- Feb. 2, 1971 2Sheets-Sheet 2 Ill s/v A .Wm @7 ,w

United States Patent O 3,560,369 RETORTING OIL SHALE INCLUDINGAGGLOMERATED FINES Chester A. Rowland, Shorewood, and Robert D. Frans,

3,560,369 Patented Feb. 2, 1971 lCe and Apparatus for the Recovery ofOil From Shale by Indirect Heating; and Robert D. Frans, Ser. No.705,989, led Feb. 16, 1968, and entitled Method and Apparatus for theRecovery of Oil From Shale by Gases of Fuel Burned External Thereof; andis related to further irnllgflllegloynvgnyasslgnors to Ams'chalmersManu' 5 provements tothe method-process concepts disclosed and FiledJune 5 1968 SELNL 734,667 cialmed thereln, and 1n copending U.S. patentapphca- Int, CL Clog 7/02 t1on of Chester A. Rowland and `Robert D,Frans, Ser. US, Cl. 208-11 3 Claims No. 734,666, liled June 5, 1968, andentitled Traveling l0 Grate Method for the Recovery of Oil From Shale.ABSTRACT oF THE DISCLOSURE BACKGRO'UND 0F I NVENTION A `system isdisclosed for recovering oil from oil bear- Fleld of the Inventum ingshale rock in which the rock is screened to separate This inventionrelates to cross-flow transfer of heat rines from larger particleshaving a dimension of at least 15 and nllSS betWeen Particulate materieland heated gases about 1A inch. The system includes a retorting zone inSuch as may be applied, fOr example, t0 processes and which heatedgases, reducing or neutral, are passed apparatus for the recovery of oilfrom carbonaceous mathrough the larger particles and agglomerates of thefines terials including oil shale of the character found in the to heatthese particles and agglomerates t0 Oil educting State 0f COlOIadO. Inparticular, this iIlVeDtiOn iS directed temperature and after which thegases, then containing to a method utilizing certain heavy fractions ofoil educted educted oil, are passed through a zone in which particlesfrom Shale, 3S a hinder in an agglomerate of Shale fines; andagglomerates are preheated and the gases cooled to arranging SnChagglomeretes and other Particles of Shale condense the oil to smalldroplets and vapor in the gases. in a multilayer hed on an aPPerituS ofthe horizontal The oil is separated from the gases and into varioustraveling grate type; and passing gases therethrough in fractions. Theheaviest fractions of the oil, representing 20 a path transverse to thepath of material movement. an amount in a range of from about 5% to 50%of the total oil educted, are recirculated through the system byDescription of the pnor art using such oil as binder to agglomerate thenes into United States Bureau of Mines Bulletin 635 publishedagglomerares of at least iz, rrreh. These agglomerares in 1966 statesthat 53 companies were producing oil from may be advantageously utilizedby charging them to a Coal and shale in 1860 but the discovery of liquidoil in traveling grate apparatus with the larger particles to form theUnited States in i859 Soon ended that industry in the a bed, with theagglomerares forming arr intermediate United States. This bulletin tellsabout the rapid rise in layer between upper and lower layers of thelarger par- Consumption of Petroleum Products that eventuellll retieles.The larger particles will, rrr a prehearrrrg e0rrderrs sulted in arevived interest in searching for an oil shale irrg zene, trap andprevent escape from the bed, dust and retorting system that would besatisfactory from a standdrops of heavy binder oil (which may escapefrom agpoint of economics, operability and the character of oil.glomates). With either an upilow or downilow of gas Produced` in thispreheating-condensing zone, heavy binder oil at- The Bureau of Minesbulletin states that oil shale tempting to escape the bed will adhere toand coat parretorts may be divided into four general classes based onticles in the upper or lower layers and dust attempting the method ofheat application:

Class Method 0i heat application Examples I Heat is transferred to theshale through a Wall Pumpherst'on Hayes, Berg. Il Heat is transferred tothe shale from the combustion occurringinthe N-T-U, Union Oil Co.,Pintsch, Bureau of Mines gas-combustion.

retort by burning product gases and the residual carbon in the IIIiiasnhsiiired to the shale by passing previously heated gases SwedishIndustrial, Bureau of Mines gas-now, Royster.

or liquids through the shale bed. 1V Heat is transferred to the shale byintroduction of hot solids into the Standard Oil Co. iluidized bed,Bureau of Mines hot-solids-contaet,

retorting bed.

Apsco, TOSCO.

to escape the bed will adhere to the larger particles coated by theheavy binder oil. Thus, both the heavy binder oil and dust attempting toescape in this preheating-condensing zone will be trapped in the bed. Inthe retorting zone such heavy fraction binder oil retained in the bedwill pyrolyze to produce further useful lighter oil, which will leavethe bed as vapor, and residual coke which will remain in the bed.

CROSS-REFERENCE TO RELATED PATENT APPLICATION Further informationrelating to these prior art systems may be found in the Bulletin andreferences cited therein. An index of patents, issued by the UnitedStates and other nations, relating to the mining and retorting of oilshale and the recovery of its products, has been published by the UnitedStates Bureau of Mines as Bulletin 468, in 1948 (650 pages). A threepart supplement identified as Bulletin 574 was published in 1958 (PartI, 134 pages; Part Il, pages; and, Part III, 62 pages).

As will be explained later, the methods and apparatus disclosedhereafter with reference to the present invention may be applied toClass II and Class III systems for ing grate. Certain of prior artpatents including some ing grate. Certain of prior art patientsincluding some related to fields other than oil shale, providedisclosures useful in describing the evolution of the present inventionand these will now be specifically discussed.

The evolution of horizontal traveling grates in the held of retortingoil shale may be illustrated by reference to a few patents, such as U.S.1,317,514 of 1919; British Pats. 278,694 and 278,740 of 1928; U.S.2,269,025 of 1942; and,

3 U.S. 3,325,395 of 1967. Of these patents only U.S. 3,325,- 395suggests forming a bed of shale particles segregated to form threelayers.

It was recognized, in U.S. 3,228,869 of 1966, that certain heavyfractions of the oil educted from shale rock, were undesirable ascomponents of a fiuid oil product requiring transport and furtherfractionating into useful commercial oil products. This patent suggestednot only that such heavy fractions be removed from the oil, but alsothat such unwanted oil fractions be utilized in processing shale rock sothat the values of such oil fractions are not lost.

In fields other than shale retorting, many processes have been developedthat involve agglomerating fines into briquettes, balls, flakes or cakesbefore processing at high temperatures. Many different materials havebeen suggested as an additive to provide a binder when makingagglomerates of lines. U.S. 2,325,840 of 1943 recognizes that it waspreviously known that certain heavy oil products, such as tar andasphalt, were useful as binders for fuel briquettes. It was alsorecognized, for example in U.S. 1,926,032 of 1933, that agglomerates offines could be utilized in a multilayer bed of material to be processedin a horizontal traveling grate type furnace.

All of the aforementioned prior art patents, while helpful to understandthe evolution of the technology, suggest agglomerate compositions, bedformations on traveling grates with particle size arrangements, andsystems, different than are involved in the present invention and thatwill hereinafter ybe described.

SUMMARY OF THE INVENTION The objects of the present invention aredirected to a search for a method and apparatus for the recovery of oilfrom oil bearing material, which is satisfactory from the standpoints ofeconomics, operability, and character of the oil recovered; and toachieve to the greatest extent possible nine requirements that have beendened by the United States Bureau of Mines and set forth in Bulletin 635(page 6). The nine requirements for a desirable system there set forthare the following:

(1) It should be continuous.

(2) It should have a high feed rate per unit cross sectional area.

(3) It should have high oil recovery efficiency.

(4) It should require a low capital investment, and possess a highoperating time factor with low operating costs.

(5) It should be thermally self-sufficient; that is, all heat and energyrequirements should be supplied wlthout burning any of the product oil.

(6) It should be ameanable to enlargement into hlghtonnage retortsrather than to a multiplicity of small units.

(7) It should require little or nol water because the Green River oilshale deposits are located in an arid region of the State of Colorado.

(8) It should be capable of efficiently processing oil shale of areasonable wide range of particle sizes to minimize crushing andscreening.

(9) It should be mechanically simple, easily operable.

Another object of the present invention is to provide an improved systemfor educting oil from oil bearing material, utilizing fines of themateral and less desirable heavy fractions of oil educted fromagglomerates of the ines of the material, with the heavy oil fractionsused as a binder additive in the agglomerates of the fines to recyclethe less desirable heavy fractions of oil through the system in theagglomerates while educting oil from the agglomerated material.

Another object of the present invention is to provide an improved systemfor educting oil from oil bearing material, utilizing fines of thematerial, larger particles of the material and less desirable heavyfractions of oil educted from agglomerates of the fines and largerparticles, with the heavy oil fractions used as a `binder additive inthe agglomerates of the iines to recycle the less desirable heavyfractions of oil through the system in the agglomerates while eductingoil from the agglomerated iines and larger particles of the material.

Still another object of the invention is to provide an improved systemfor educting oil from a multilayer bed of oil bearing rock on ahorizontal traveling grate furnace with improved retention of nes withinthe bed, t0 eHiciently utilize fines, larger particles of the rock, andless desirable heavy fractions of oil educted from agglomerates of thefines and larger particles; and with the heavy oil fractions used as abinder in the agglomerates of the iines to recycle the less desirableheavy fractions of oil through the system in the agglomerate whileeducting oil from the rock and pyrolyzing the heavy binder oil toproduce additional quantities of useful lighter oil and residual coke.

In the following description of how these objects are attained, andclaims related thereto, a stream of gases will be referred to as anoncondensable combustible gas stream, either oxygen free or mixed withcombustion air. By this terminology it is meant gases such as are drivenfrom shale rock heated in an oxygen free atmosphere and these gases area mixture of carbonaceous gases including light hydrocarbon fractions,hydrogen, nitrogen and other gases in trace amounts. By referring tosuch a gas stream as being noncondensable, it is meant that the gasstream cannot be condensed, as a practical matter, with equipment and inenviroments such as are herein disclosed or found in oil refineries; andthat these gases are therefore of a character similar to those producedby oil refining operations which are burned at the refinery to disposeof them safely.

According to one practice of the present invention as applied to theretorting of oil bearing shale rock on a horizontal grate, the shale iscrushed and screened to provide particles larger than about 1A: inch andseparate therefrom smaller particles which will be referred to as nes.The fines may be mixed with a binder additive, tne source of -which willbe explained as this description proceeds, and formed into agglomerateslarger than about 1A inch. The agglomerates may be formed inconventional agglomerating equipment, as `for example a balling drumsuch as is disclosed in U.S. 2,411,873 of 1946. The agglomerates andlarger pieces may then be formed into a multilayer bed on a horizontaltraveling grate, with the agglomerated fines occupying a middle layerbetween an upper and lower layer of the larger size particles. This bedof material may then be transported tnrough at least a materialpreheating and oil condensing zone; a retorting zone where oil iseducted from the shale; and a cooling zone. A stream of oxygen freecombustible gas, the source of which will be explained later, ispreheated by passing through shale in the cooling zone. The preheatedgas is delivered to a combustion chamber where a controlled amount ofcombustion air is mixed with the preheated gas (and if desired anadditional nonpreheated quantity of the gas stream for added temperaturecontrol purposes) in such quantities as are necessary to provide forcombustion that provides an oxygen free gas stream at about 1200 to 1600F. The oxygen free combustion gases at about 1200" to 1600 F. then passthrough the shale in the retorting zone to educt oil and quantities ofthe noncondensable oxygen free cornbustible stream of gases from theshale, and then througn the shale in the material preheating and oilcondensing zone where the educted oil is condensed and becomes suspendedas a stable mist in the oxygen free noncondensable combustible gasstream from which the oil may be mechanically separated. This gasstream, after the oil is separated therefrom provides the gas stream,previously referred to, that cools spent shale and is thereafterpartially burned to efficiently utilize this fuel heat source to theextent necessary to provide the desired oxygen free gas stream at 1200to 160 F. The oil separated from the gases is itself separated into atleast two portions with one portion being the heaviest fractions of theoil and representing an amount of from 5% to 50% of the total (andheaviest) oil educted from the material. This portion of the oilcontaining the heaviest fractions is the binder additive previouslyreferred to as being mixed with the fines to form agglomerates. Withthese agglomerates of fines occupying a middle layer in the bed, betweenlayers of the larger particles of rock, the bed is carried through thepreheatingcondensing zone. As the gas stream passes through the layersof material in this zone the larger particles will trap and prevent theescape from the bed, dust and drops of heavy binder oil (which mayescape from the agglomerates forming the middle layer of the bed). Witheither an upflow or downflow of gas in this treating zone, heavy binderoil attempting to escape the bed will adhere to and coat particles inthe upper or lower layers (depending upon whether gas flow is up ordown) and dust attempting to escape the bed will adhere to the largerparticles coated by the heavy binder oil. Thus, both the heavy binderoil and dust attempting to escape in this zone will become trapped inthe bed. In the retorting zone the heavy fraction binder oil retained inthe bed, Whether in agglomerates or coating particles of rock, willpyrolyze to produce additional quantities of useful lighter oil, whichwlll leave the bed as vapor, and residual coke which will remain in thebed.

Other features and objects of the invention and how such have beenattained by this invention will appear from the more detaileddescription to follow with reference to an embodiment of the presentinvention shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l shows diagrammatically anapparatus to which the present invention has been applied and includinga horizontal traveling grate shown in side elevation and in section; and

FIG. 2 is a flow diagram showing the manner in which materials flow fromone operation and apparatus to another in a system according to thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODI- MENT Referring to fFIG. 1 of thedrawing, a gas permeable traveling grate assembly 1 defines a loop withan upper strand 2 supported between head and tail shafts 3 and 4 formovement in a generally horizontal path in the direction indicated byarrows. A housing assembly 5 is arranged below and over the upper strand2 and baffles t6, 7 above strand 2 and bafes 8, 9 below strand 2 dividethe interior of the housing assembly 5 into at least three chambers 15,16 and 17 above strand 2 and -windboxes 19, 20 and 21 beneath strand 2and in vertical alignment with the chambers 15, v16 and 17,respectively. A feed hopper assembly 22 having three feed chambers 22a,22b and 22C is provided for feeding, through chamber 22b, agglomeratednes on top of and beneath particles of rock feed through chambers 22aand 22e, to provide a three layer bed of material on strand 2. Acombustion chamber 25 is provided remote from strand 2 and housingassembly 5. An oil separator station is indicated at 30, which may beone or more mechanical oil-gas separators, with or without gas coolersas desired. The oil-gas separating operation is also located apart fromthe strand 2 and housing S. Separators suitable for the use that will bedescribed are known to this art and an example of a patent disclosingsuch a device is U.S. 2,386,196 of 1945.

A gas stream conveying system connects the grate assembly 1, thecombustion chamber 25 and the separator 30, in a manner that will now bedescribed. The gas stream conveying system includes a blower 40 and afirst conduit 41 for delivering gas to windbox 21. A second conduit 42with a blower 43 is provided for delivering preheated gas to combustionchamber 25. Gas ow communication from the first conduit 41 to the secondconduit 42 is by a path established through windbox 21 and material onstrand 2 in chamber 17. A gas stream passing from conduit 41 6 throughmaterial on strand 2 to conduit 42 thereby cools the material and isitself preheated before entering combustion chamber 25.

A third conduit 44 is connected to combustion chamber 25 for deliverythereto combustion air. Means for controlling the combustion airadmitted to chamber 25 is indicated by the valve 45. A- fourth conduit46 is connected to combustion chamber 25 to exit an oxygen free mixtureof combustion products and noncondensable combustible gases and deliversuch gases to the retorting chamber 16. The gas discharged by conduit 46to chamber 16 passes downward through material on strand 2 in chamber16. A .fth conduit 47 is connected to windbox 20 to provide an exittherefrom and establish gas ow communication from the fourth conduit 46through the upper strand 2 of the grate assembly 1 to the fth conduit47. A blower 48 is provided in conduit 47 to blow gases from windbox 20into windbox 19 and up through strand 2 and into chamber 15. A sixthconduit 49 is connected to chamber 15 and to the oil separator 30. Ablower 50 is provided in conduit 49 to deliver to the separator 30liquid oil (mist) and a stream of noncondensable combustible oxygen freegases educted from the shale. The stream of gases passing out of chamber16 through windbox 20 and conduit 47 is of greater quantity than thequantity of the gas stream passing into chamber 16 from conduit 46. Thisis true of course because as the heated gas stream passes through theshale, vaporized oil and noncondensable gases are educted from the shaleand added to the gas stream.

Liquid oil from the shale separated from noncondensable gases at 30 maybe discharged through an exit at 51 and led off to oil refiningapparatus (not shown). The stream of noncondensable combustible gasesfrom the separator at 30 may be discharged through an exit at 52 to aseventh conduit 54 which is connected to the rst described conduit 41.Thus the stream of noncondensable combustible gases educted from theshale supplies the need for an oxygen free nonburning gas stream to coolthe shale material in chamber 17 and the need (after being preheated andmixed with combustion air from conduit 44) for a burning stream of gasesfor heating the shale material in the retorting zone 16. An eighthconduit 55 is connected on one end to separator gas exit 52 to deliversome of the gas from separator 30 to combustion chamber 25 withoutpassing through material on strand 2. Means for controlling this ow isindicated by the valve 56.

Because burning fuel in combustion chamber 25 and heating the shale inretorting chamber 16 generates additional volumes of gases which arecontinuously added to the system, a bleed off will be necessary and maybe provided as at l57.

An agglomerating device, such as the balling drum `60 shown in FIG. 1,is feed fines by a conveyor 61 and heavy binder oil through conduit 62.Drum 60 mixes and agglomerates the material fed thereto and dischargesagglomerates to a conveyer 63 for delivery to chamber 22h. The ballingdrum -60 may be of the type disclosed in U.S. 2,411,873. The heavybinder oil delivered to drum 60 by conduit 62 comprises heavy fractionsof the oil discharged from the oil-gas separating apparatus 30 to afractionator at 51. The fractionator (not shown, except for its locationin the system being indicated) may be a vacuum fractional distillationcolumn operated to divide the oil into two portions, one of lightfractions and the other of heavy, i.e., high boiling point, fractions(with the heavy fraction portion being between 5% and 50% of the totalvolume of oil) as is described in the previously mentioned patent U.S.3,228,869. In the best interests of an overall process, such as will bedescribed later with reference to FIG. 2, the amount of oil recycledthrough the system as binder oil would be advantageously adjusted withinthe 5% to 50% range referred to, according to changes in weather. Thatis, in cold weather more heavy fractions would be desirably removed andrecycled to maintain the desired flowability of the lighter oils shippedor pumped to a refinery.

To operate an apparatus such as shown in FIG. 1 and apply thereto themethod of operation of the present invention, shale rock that has beencrushed and screened to provide pieces at least about Mi inch (the uppersize limit is not important to this invention and may be as desired,perhaps for example about 2 inches). These pieces are charged to feedhopper chambers 22a and 22C. The feed hopper 22 discharges suchparticles of crushed shale on the upper strand 2 of the grate assembly 1which is driven by means (not shown) to move the grate in the directionshown by arrows. Agglomerates of nes formed in drum 60 are screened, asindicated in FIG. 2, to recycle pieces smaller than about 1A inch andthe agglomerates that are larger than about 1A inch are charged to feedhopper chamber 22b which discharges this size fraction as a middle layerupon strand 2 thus forming a three layer bed on strand 2. The grate 1carries the bed of shale through the chambers 15, 16 and 17, which inthe practice of this embodiment of the invention define a downstreammaterial ow sequence comprising a shale preheating and oil condensingzone (in chamber a retorting and oil educting zone (in chamber 16); and,a cooling zone (in chamber 17).

After the shale material has given up oil as a vapor and noncondensablegases while in chamber 16 the residue is moved through the cooling zonein chamber 17 where gas from separator at perhaps 100 F. is blown byblower through the first conduit 41 upwardly through windbox 21, strand2, and into cooling chamber 17, to cool the material thereon to atemperature for handling by rubber conveyer belts or the like, andpreheat the gas to perhaps about 860 F. The preheated gas passes fromchamber 17 into conduit 42. This preheated air is then drawn in byblower 43 and delivered to combustion chamber 25 where controlledamounts of combustion air from conduit 44 and gases from conduit 55 mixtherewith to burn a portion of the combustibles therein. Valve 45controls the air flow through conduit 44 and provides a primary controlto cause sufiicient combustion 0f gases from conduit 42 to occur toprovide a mixture of unburned noncondensable gases and combustionproducts, free of oxygen, to exit from combustion chamber 25 throughconduit 46 at about 1200" to 1600" F. Conduit 46 delivers these gases tothe retorting chamber 16. Valve 56 provides additional control of thecombustion taking place in chamber 25. These gases from conduit 46 passdownwardly through the shale on strand 2 in chamber 16 and heat theshale to at least slightly above oil educting temperature which may beexpected to be about 800 F. The gases drawn from windbox 20 at slightlyabove educting, condensing temperature are blown through conduit 47,windbox 19, and through the shale on strand 2 in chamber 15. Thecondensable vaporized oil and noncondensable gases educted from theshale in the retorting chamber 16, along with the hot gases from conduit46, are passed through the bed of shale in chamber 15 which condensesthe oil vapors to a stable mist while preheating raw shale from hopper22. Oil mist and a stream of noncondensable combustible gases exit lfromchamber 15 through conduit 49 at about 250 F. and are delivered to themechanical oil-gas separating station 30. Multistage separating, perhapsincluding or resulting in further cooling, may provide gases in conduits54, 41 and 55, 44 at about 100 F.

A complete process, including the method of operation that has beendescribed with reference to the apparatus of FIG. l, will now bedescribed with reference to the fiow diagram of FIG. 2.

As indicated by the legend labels in FIG. .2, oil bearing shale isdelivered to a crushing and/or grinding operation and then to ascreening operation that separates pieces which may, for example, belarger than Mi inch,

from smaller pieces which are referred to as fines. The plus 1/4 inchparticles are delivered to a retorting stage indicated by a box solabeled and additionally labeled with the reference numeral 1 toindicate that this stage may include the entire assembly identified withthe numeral 1 in FIG. l. The particles delivered to this stage aredischarged into the feed hopper assembly 22, which is also indicated atthe box 1. Fines from the screening operation are indicated in FIG. 2 t0be carried by the conveyor 62 to an agglomerating stage, which may bethe balling drum `60 of FIG. l. As shown in FIG. 2, agglomerates fromdrum 60 may be screened with fines being recirculated through theagglomerating stage and the agglomerates at least about 1A: inch in sizeare delivered by the conveyor 63 to the feed hopper assembly 22. Oil (asmist) and gas from the retorting and condensing stage 1, are deliveredby the conduit 49' to a gas-oil and light oil-heavy oil separationstage. The gas from this stage passes into conduit 52 for uses indicatedin FIG. l. The light oil fractions may be delivered or conveyed asindicated in FIG. 2 to a refinery, and this may be accomplished by suchas pipe lines or tank cars as desired. The heavy oil fractions areconveyed by conduit 61 to agglomerating drum 60 for use therein as abinder additive.

With the apparatus and method of its operation described with referenceto FIG. l, and the overall process incorporating the aforesaid anddescribed with reference to FIG. 2, it has been shown how to efficientlyutilize nes and larger particles of an oil bearing rock, and lessdesirable heavy fractions of oil educted from both particles of the rockand agglomerated fines of the rock. This has been accomplished by novelconcepts including such as utilizing the heavy oil fractions as a binderadditive in the making of agglomerates of the fines. With suchagglomerates and pieces arranged in a multilayer bed for treatment inpreheating-condensing and retorting educting zones according to thepresent invention, nes and droplets of heavy binder oil are trappedwithin the bed and the heavy binder oil is pyrolyzed to produceadditional quantities of lighter more commercially valuable oil andresidual coke.

The manner in which and the fractions into which the educted oil isdivided, for recycling versus commercial refining, is subject to somevariation. For example, in moderate climates or during warm summermonths, it may be possible to reduce the percentage of educted oil thatis recycled because warm weather will make it easier to pump an oilmixture including more of the heavier fractions Likewise during coldweather more of the heavier fractions may have to be removed from theoil in order to efficiently pump the oil, thus resulting in a need torecycle more of these heavy oils as a binder additive in agglomeratedfines.

From the foregoing detailed description it has been shown how theobjects of the invention have been attained in a preferred manner.However, modification to (for example, described temperature ranges,particle sizes, percentage of oil recycled, etc.) and equivalents of thedisclosed concepts such as readily occur to those skilled in the art areintended to be included within the scope of this invention. Thus, thescope of this invention is intended to be limited solely by the scope ofthe claims such as are or may hereafter be appended hereto.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method of recovering oil from oil bearing shale comprising thesteps of:

(A) separating said shale into particles larger than about 1A inch andsmaller particle fines;

(B) agglomerating said fines with a subsequently derived heavy productliquid oil to form agglomerates larger than approximately 1A inch;

(C) forming said agglomerated fines and said larger particles of shaleinto a multilayer bed on a horizontal traveling grate, with theagglomerated layer occupying a middle layer between an upper and a lowerlayer of the larger size particles;

(D) retorting said multilayer bed by passing into contact therewith astream of noncondensable oxygen free gases heated to at least thetemperature required to vaporize and educe the oil as a vapor into thegas stream;

(E) cooling said gas stream containing entrained vaporized oil tocondense the oil vapor to a mist;

(F) separating the oil mist from the gas stream;

(G) dividing the oil into at least two portions with one portioncontaining heavy liquid fractions in an amount of between and 50 percentof the total quantity of oil; and

(H) recycling said heavy fractions portion of the oil by mixing saidheavy fractions portion as a binder additive with said nes to producesaid agglomerates as oil bound agglomerates of said nes for retorting ashereinbefore set forth in this claim.

2. In a method according to claim 1, wherein said bed on said horizontaltraveling grate passes through a first zone in which said material ispreheated by passing through said bed a gas stream containing entrainedvaporized oil to cool said gas stream while said oil vapor in saidpreheating gas stream is condensed and a second zone in which saidmaterial is retorted.

3. In a method according to claim 2, wherein said bed on said gratepasses from said second zone through a third zone in which said bed ofagglomerates and discrete particles are cooled by the gas stream fromwhich the oil mist has been separated and after said bed is cooled andthe gas stream is thereby again heated the gas stream is delivered to acombustion chamber for further heating to said temperature required toeduce oil from said material, after which said gas stream re-enters saidsecond zone to retort said material.

References Cited PATRICK P. GARVIN, Primary Examiner P. E. KONOPKA,Assistant Examiner U.S. Cl. X.R.

